1. Field of the invention
The invention relates to a neutral electrode for high-frequency surgery which conducts a high-frequency surgical current from a patient and has at least first and second flat partial electrodes which are separated from each other by an insulating strip. The invention further relates to a terminal clamp for such a neutral electrode.
2. Description of the Prior Art
A split neutral electrode for high-frequency (HF) surgery (i.e., one which operates with two flat partial electrodes) has been described, for example, in German Utility Model (GM) Patent 82 05 363. As described therein, monitoring of the effectiveness of the electrical connection to the patient is accomplished by means of a control circuit using a low frequency control current. The control current flows from the contact surface of one partial electrode through the skin of the patient, to the contact surface of the other partial electrode.
German patent application publication DE-OS 28 49 422 describes another two part (i.e., split) neutral electrode.
Single neutral electrodes are also known in the present state of the art. HF-surgical apparatus is often equipped with a monitoring circuit with which it may be determined if the single electrode is in fact operational i.e., connected. For this purpose, first and second connecting leads are attached to the surface of the single part electrode. A control current is caused to flow from the first connecting lead through the neutral electrode to the second connecting lead. If the control current exceeds a pre-set threshold value, it may be safely assumed that the single electrode is in fact operational and has not lost sufficient electrical contact and/or fallen off. The embodiment of the neutral electrode proposed herein relates especially to this type of monitoring circuit.
It is now established that surgical procedures using a neutral electrode of the multiple partial electrode type are also desirable. A monitoring circuit is employed during the surgical procedure to determine whether the neutral electrode has large surface contact with the patient or just limited surface contacts. A monitoring circuit of this kind is described in a U.S. Patent Application by the same applicant and assignee herein, entitled "Method and Apparatus for Monitoring the Surface Contact of a Neutral Electrode of a HF-Surgical Apparatus", filed concurrently with the present application. It is desirable to form such a two or multiple partial neutral electrode in such a manner that it can be employed with a conventional monitoring circuit (i.e., one intended for use with a single neutral electrode) to make it possible to test whether the neutral electrode is in fact connected to the HF-surgical apparatus. This desire encounters the following difficulty: When one or more insulating strips are provided between the partial neutral electrodes, a direct current (or a low-frequency alternating current) applied to the neutral electrode cannot be used to check whether they are are present, since there can be no current flow between the partial electrodes due to the insulating strips.